You might have expected a backlash against Michael Frayn's Democracy, which walked off with nearly all the Best Play awards of 2003, on the surely-nothing-can-be-that-good principle. But seeing the piece again in its West End transfer to Wyndhams makes me feel that, if anything, my rave review of the Cottesloe premiere erred on the side of niggardliness.

The play begins in 1969 as Willy Brandt (Roger Allam) accepts the Chancellorship of the Federal Republic - the first Social Democrat to have held the office in 40 years. It proceeds to give the audience a crash course in the extremely complicated coalition politics of post-war Germany. The penetration and panache with which Frayn achieves this resides in the perfect marriage he has arranged between exposition and thematic development. For we see the wheeler-dealings of the West German men in suits through the eyes of Günter Guillaume (Conleth Hill), the Stasi spy who, through a combination of tactical nonentity, ever-helpfulness and always being there at the right time, became Brandt's right-hand man, confidant and reluctant nemesis. Beautifully served by Michael Blakemore's miraculously clear production, the play is light on its feet and on its wits as it flicks back and forth between re-enactment and Guillaume's running commentary to his East German controller (Michael Simkins).

The play uses the ideologically divided Germany of the Cold War period and the dubious hand-to-mouth coalition-cobbling as a searching metaphor for the contradictions in all of us that arguably make democracy the least bad form of government. Through characters such as the old ex-Marxist fixer Herbert Wehner (brilliantly played by David Ryall), Frayn's play acknowledges all the imperfections in the democratic process while floating the theory that democracy answers better than any other form of government to a truth about our inner lives. At one point Brandt quotes Walt Whitman's famous line: "Do I contradict myself? Very well, I contradict myself. I am large: I contain multitudes." The implication is that within each of us is a jostling hubbub of selves who need to be able to elect (and throw out of office) a leader.

The play also strikes me now as an extended pun on the meaning of "identity", a contrary word that can signify both that which makes us individuals and the state wherein two things are identical. In masterly scenes between Chancellor and spy, Frayn teases out the ways in which these two fatherless, womanising, fatalistic men have, through the pressure of history, arrived at a similar sense of self-alienation. Allam superbly brings out the haunting remoteness (from self as well as others) at the heart of Brandt's gregariousness, while Hill has a wonderful glint of the nerdy, worshipping fan whose adoration could prove fatal to its object. Unmissable.